This project will investigate the molecular basis for the defects in certain inherited disorders of aging in humans: Werner syndrome and progeria. Although rare, these diseases represent an opportunity to study the aging process in general and the particular case of two human diseases which affect this process. Each of these disorders represents a single gene defect. We will apply fusion techniques to complement defects which are manifest in cells form patients with these diseases. The complemented cells will allow the identification and isolation of the gene for these diseases. As a long range goal, the function of the gene product in normal cellular function and in aging will be analyzed.